Low profile circuit breaker with staggered terminals

ABSTRACT

Low profile high voltage truck mounted switchgear having upper back disconnect studs and contacts and lower back disconnect studs and contacts in which the lower back disconnect studs and contacts extend beyond the truck and the upper back disconnect contacts are stepped back toward or above the switchgear in the truck to produce the proper electrical clearance and spacing on a diagonal line in a vertical plane. This structure makes it possible to produce a low silhouette which may more readily be camouflaged for environmental beautification and obviates the need for spacing the axes of the upper and lower back disconnect studs by the full vertical distance necessary for proper electrical clearance and spacing. The volume of the entire assembly including the switchboard housing may be reduced since the horizontal length of the switchgear truck need not be increased; while a portion of the housing, as for instance the part containing the supply bus, may overlie a portion of the truck and lower back disconnect stud and contact when the switchgear is placed in the switchboard.

nite States Patent 91 Brandt, Jr. et al.

[451 May 22, 1973 [54] LOW PROFILE CIRCUIT BREAKER WITH STAGGERED TERMINALS [75] Inventors: Thomas F. Brandt, Jr., Swarthmore; Philip C. Netzel, Milmont Part, both of Pa.

Primary Examiner-R0bert K. Schaefer Assistant Examiner-M. Ginsburg Attorney-Ostrolenk, Faber, Gerb & Soffen ABS'I RACT Low profile high voltage truck mounted switchgear having upper back disconnect studs and contacts and lower back disconnect studs and contacts in which the lower back disconnect studs and contacts extend beyond the truck and the upper back disconnect contacts are stepped back toward or above the switchgear in the truck to produce the proper electrical clearance and spacing on a diagonal line in a vertical plane. This structure makes it possible to produce a low silhouette which may more readily be camouflaged for environmental beautification and obviates the need for spacing the axes of the upper and lower back disconnect studs by the full vertical distance necessary for proper electrical clearance and spacing. The volume of the entire assembly including the switchboard housing may be reduced since the horizontal length of the switchgear truck need not be increased; while a portion of the housing, as for instance the part containing the supply bus, may overlie a portion of the truck and lower back disconnect stud and contact when the switchgear is placed in the switchboard.

8 Claims, 4 Drawing Figures PATENTEDHAYZZIQTS SHEET 2 OF 3 I N VENTORS THOMAS BRA/vane PH/A A C A/grzg;

AffQQ/VEXS LOW PROFILE CIRCUIT BREAKER WITH STAGGERED TERMINALS This invention relates to switchgear and more particularly to a low profile circuit breaker in which the rear terminals or disconnect structure are so arranged that the upper and lower disconnect terminals are staggered with respect to each other in a vertical plane, thereby making it possible to substantially decrease the height of the circuit breaker structure.

The essential element of the invention is that appropriate electrical spacing between the upper and lower rear disconnect contacts of the circuit breaker is achieved not by merely spacing the contacts vertically by a sufficient distance to obtain the desired spacing, but by stepping the rear disconnect studs and contacts so that appropriate spacing is provided between the upper and lower rear disconnect contacts even though the vertical height is substantially less, the spacing being achieved along an inclined line.

A further advantage of the low profile stepped rear disconnect stud and contact structure is that it becomes possible to arrange the circuit breaker and the supply bus in such manner that the supply bus actually overlies a substantial part of the lower section of the rear of the circuit breaker structure owing to the stepped arrangement of the rear disconnect contact; the low profile structure and the stepping of the rear disconnect studs and contact therefore result in a vertically shorter circuit breaker structure. This effect need not necessarily increase the total volume of the breaker switchboard and may actually result in a reduction of the volume thereof.

The concept of the low profile circuit breaker stems from the desire on the part of utility companies and the actual need in the communities to arrange electrical supply and control structures in such manner that they become less visible, less obtrusive and more capable of camouflage by shrubbery, fencing or other devices or structures.

The present invention by reducing the vertical height of the circuit breaker structure and actually creating a composite structure which may occupy a lesser volume, while initially designed with the concept of making a structure which is low enough to permit camouflage or concealment, has actually produced other ad vantages notably the decrease in volume of the entire structure.

Heretofore in the construction of truck mounted circuit breakers for substantial voltages of for instance of the order of 38 KV it has always been thought neces sary to arrange the truck mounted circuit breakers so that the rear disconnect contacts would be parallel to each other, i.e., the lower rear disconnect contacts of a three pole truck mounted circuit breaker structure would be exactly parallel and terminate in the same plane as the upper rear disconnect contacts. As circuit breakers increase not only in size but in the voltages and currents which they are intended to interrupt, the spacing between the upper and lower rear disconnect contacts in order to provide appropriate electrical spacing for the voltages involved have become greater and greater. This has resulted in a very substantial corresponding increase in the vertical height of the circuit breaker mounting means in order to obtain the desired spacing between the rear disconnect contacts. By staggering the rear disconnect contact studs and the rear disconnect contacts thermselves horizontally with respect to each other, the same or greater spacing may be obtained between the uper and lower rear disconnect contacts in a vertically shorter structure.

The primary object of this invention therefore is the provision and construction of low profile switchgear.

A further object of this invention necessarily entailed by the concept of low profile switchgear, such as circuit breakers, is the arrangement of the upper and lower rear disconnect contacts of switchgear in such manner that the contact elements of the upper set of rear disconnect contacts are stepped with respect to the contact elements of the lower rear disconnect contacts thereby maintaining the desired electrical spacing between the contacts in a lesser vertical height.

A further object of this invention is the provision of a switchboard in which a compartment or section, which may have a supply bus or other elements, actu ally overlies a lower portion of the truck mounted circuit breaker when the truck is inserted-in the switchboard thereby making it possible to achieve the further object of the reduction in the overall volume of the entire switchboard including the housing for the supply bus and the truck mounted circuit breaker.

The foregoing and many other objects of this invention will become apparent in the following description and drawings in which:

FIG. 1 is a schematic view of the novel truck mounted circuit breaker showing the stepped disconnect contacts and the manner in which the supply bus may overlie a portion of the truck mounted circuit breaker when the breaker is inserted in the switch board.

FIG. 2 is a view in perspective of the side and front of a truck mounted circuit breaker following the principles set forth in the schematic view of FIG. 1.

FIG. 3 is a side view of one of the poles of the truck mounted circuit breaker of FIG. 2.

FIG. 4 is a front view of a portion of the truck mounted circuit breaker of FIG. 3.

Referring first to the schematic view FIG. 1, there is here shown a truck 10 in which is mounted a circuit breaker which in turn is provided with back connector studs consisting of an upper set of back connector studs 11 and a lower set of back connector studs 12 each terminating in back disconnect contacts 40. The truck is provided with appropriate apparatus not here shown but which is well understood in the art which permits the truck to be racked out and moved in to the circuit breaker switchboard on the wheels 13, 13. The usual structure of a truck mounted circuit breaker mounted in a truck of the type generally shown at 10 of FIG. 1 provides for three parallel interrupting mechanisms usually controlled by a single operating mechanism each of the physically parallel interrupting mechanisms being utilized to control a single phase of the supply from the bus structure 14 in the housing 15 in the switchboard 16. a

A separate pair of upper and lower back disconnect studs 11 and 12 is associated with each of the phases of 14a, 14b, 14c of the bus structure 14 and is thus connected with an appropriate stationary contact'l7 for the particular bus run when the circuit breaker is connected in the switchboard. Similarly the lower disconnect contacts 12 are connected to a load circuit in the switchboard 16, the said load circuit being connected to connector 18, an individual load lead or bus being connected to each of the three lower disconnect contacts of the truck mounted circuit breaker 10.

Where high voltages are involved, appropriate isolation may be provided for the contact element 17 for each of the conductors in the switchboard 16 as for instance by shutters 20 and lower shutters 21 indicated schematically in FIG. 1, these shutters being suitably mounted in the switchboard and being so arranged that when the back disconnect contacts 11 and 12 are withdrawn either by operation of the truck as a whole or by racking mechanism carried by the truck, the shutters 20 and 21 will cover the openings to the connectors 17 and 18 and thereby further isolate them.

The essential elements of the present invention are however indicated schematically in FIG. 1 in that the upper set of back disconnect contacts 40 and the lower set'of back disconnect contacts 51 are spaced from each other by a distance which is the resultant of both a horizontal spacing and a vertical spacing. That is, in the usual truck mounted or other circuit breaker or switchgear structure heretofore known, it has always appeared to be desirable to have the back disconnect contacts 40 and 51 of the circuit breaker vertically spaced from each other by a sufficient distance to provide appropriate clearance between the upper stationary back disconnect contacts 40 and the lower stationary back disconnect contacts 51 on the switchboard as well as to provide sufficient clearance and electrical distance between the back disconnect contacts 40 and 51 of the circuit breaker itself.

In the present invention by stepping these disconnect contacts horizontally in a vertical plane, it is possible to achieve the desired spacing in an upper vertical distance provided of course that the swtichboard cooperating contacts are appropriately spaced. This stepping of the back disconnect contacts 40 and 51 to provide both horizontal and vertical spacing affords a sum total in the diagonal resultant line of sufficient electrical spacing. The circuit breaker structure will thus have an L-shaped structure including an upwardly directed support structure for the upper back disconnect contacts. This may be utilized as shown schematically in FIG. 1 by arranging the switchboard 16 so that the compartment 15 for the supply bus 14 may actually overlie the circuit breaker or a portion of the circuit breaker when the circuit breaker mounted on truck is racked into position. 1

Although the horizontal stepping of the vertically arranged upper and lower disconnects may appear at first to provide for or require additional horizontal dimensioning nevertheless the reduction in volume is achieved cooperatively by reason of the arrangement of the switchboard itself which cooperates with the recess thus created in the truck to support the supply bus in an area which normally would have been blocked off by the need for permitting entry of the circuit breaker. In addition as will be shown especially in connection with FIG. 3, the structure of the circuit breaker itself may be such and the cooperating elements may all be so arranged that the horizontal spacing of the circuit breaker truck 10 in order to step the back disconnect contacts does not actually increase the front to back dimensions of the circuit breaker structure. Thus a decrease in height and a decrease in volume are achieved over prior structures which would utilize a circuit breaker element of the same capacity. These effects will become more apparent in FIGS. 2, 3 and 4 which show an actual rather than schematic circuit breaker structure.

The truck 10 in FIG. 2 carries the operating mechanism 25 for the circuit breaker structure. As seen in FIGS. 2, 3 and 4 the circuit breaker structure comprises a pair of vacuum interrupters 30, 31 which are of well known construction each of which consists of a stationary contact 32, 32a and a moving contact 33, 33a housed in an evacuated chamber 34, 34a. The moving contact 33 in each chamber 34 has an extension 36, 36a extending outside of the housing, the moving contact being capable of longitudinal movement without disturbing the seals which maintain the vacuum owing to the fact that the moving contact as is well known in the vacuum interrupter art is provided with a bellows seal 37, 370 which permits such longitudinal movement without interfering with or creating an unnecessary break in the vacuum container 34, 34a. The essential element of a vacuum interrupter, also as is well known, is that a relatively very small movement of the contacts can interrupt very large currents at very high voltages. Thus the arrangement shown in FIGS. 2, 3 and 4 (FIG. 3 for a single pole thereof) is for .a 38 KV interrupter in which the two vacuum interrupters are in series with each other. The current enters from the bus to the stationary disconnect contact 40, to the back connection stud 41 of insulating bushing 42 to the vertical copper conductor bar 45 to the connector stud 46 on the vacuum interrupter 34 then through the stationary contact 32 of the vacuum interrupter 34, the movable contact 33 of the vacuum interrupter 34, the extension 36 of the said movable contact, the connector 47 which is electrically connected at 48 to the bridging bar 49 which is similarly connected at connector 48a to the connector 47a and then through moving contact 33a and stationary contact 32a of the vacuum interrupter 34a and the lower disconnect contact 51 and then to the appropriate stationary disconnect contact in the switchboard 16.

As shown in FIGS. 2, 3 and 4 each of the terminals 46, 46, 46 of the vacuum interrupter 34 at each pole is connected as shown to an upper disconnect stud 41. The bushing 42 for the upper disconnect stud 41 is appropriately supported in any appropriate insulating framework 53 which framework primarily is provided for the purpose of spacing the upper back disconnect stud 41 above the circuit breaker structure. The lower back disconnect sutd 50 is on a line with the aligned contacts of the series vacuum interrupters 34 and 34a.

The actual structure of the circuit breaker and all of the operating mechanism is described in application Ser. No. 192,029, filed Oct. 26, 1971, for OPERAT- ING MECHANISM FOR VACUUM CIRCUIT BREAKER INCLUDING CONTACT PRESSURE SPRINGS, which is drawn to the details of the structure, and assigned to the assignee of the present invention. The present disclosure is directed to the low profile stepped disconnect circuit breaker or swtichgear mounting means and the associated switchboard which permits the arrangement of the unit in a low profile or low silhouette construction. However, very briefly, the operating mechanism 25 consists of an operating bar 60 which carries an operating pin 61 guided in a vertical slot 62 and controlling the toggle 63, 64. The movement of the operating bar 60, in an upward direction collapses the toggle 63, 64 and through pins 65 and 66 connected to the clamps 67 and 68 draws the contacts 36 and 36a toward the operating bar or slot location 62 thereby opening the circuit breakers or interrupters; an opposite movement will result in the closing of the circuit breakers or interrupters. Since the contacts 33 and 33a must move exactly linearly, control of the lineal movement is achieved by the parallelogram arrangement comprising the additional links 70 and 71 as well as links 72, 73 all as described in the aforementioned copending application.

The lower disconnect stud in the bushing 56 is of course connected to the terminal 72' of the vacuum in terrupter 34a to which is connected the stationary contact 32a. Said stud is supported on the housing 73 by the bracket 74 so that it is aligned exactly with the line of contacts in the series vacuum interrupters.

As will be seen now not only from the schematic view of MG. 1 but especially from the partly cross-sectional view of MG. 3, the back disconnect contacts 40 and 51 are stepped horizontally from each other as well as being spaced vertically thereby providing appropriate electrical clearance on a resultant line which is a diagonal and therefore permits the required electrical clearance to be obtained without requiring the studs to be spaced vertically from each other by the distance required for such electrical clearance. The stepping of the upper back disconnect contacts and their studs and the lower back disconnect contacts and their studs thereby makes it possible to construct not only a low profile or low silhouette circuit interrupter or switch but also makes it possible to reduce the volume of the entire switchboard since the low silhouette structure of the circuit breaker or switch permits the construction of the switchboard so that a portion of the switchboard will overlie a portion of the truck carrying the circuit breaker or switch thereby making better and more efficient use of space.

With the growing desire to render utility services less and less visible and to camouflage as far as possible those aspects of the services which must be adjacent residential communities, the arrangement of the circuit breaker or switch mounting for a high voltage breaker wherein the stepping of the back disconnect contacts permits the utilization of a low profile or low silhouette and at the same time permits also reduction in the volume of the entire installation, provides an additional means for achieving the desired harmony with the environment as well as providing a compact more easily serviced structure.

In the foregoing this invention has been described in connection with preferred embodiments thereof. Since many variations and modifications may be possible and will now be obvious to those skilled in the art, it is preferred that the scope of this invention be determined not by the specific disclosures herein contained but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. In a low profile, truck-mounted switchgear unit containing at least one pair of interrupting contacts, an operating mechanism for operating said pair of interrupting contacts between an engaged and disengaged position, a racking mechanism for moving said truckmounted switchgear unit with a switchgear cubicle, and at least one pair of disconnect contacts connected in series with said pair of interrupting contacts; said pair of disconnect contacts each comprising an elongated disconnect contact stud extending horizontally away from respective first and second vertical rear surface portions of said truck-mounted switchgear unit and terminating in respective contact ends; said disconnect contact studs being parallel to one another throughout their entire lengths; said pair of disconnect contact studs being stepped relative to one another, whereby said pair of studs are laterally separated from one another such that the said contact end of one of said disconnect contact studs does not reach the lateral position of the said vertical rear surface portion from which the other of said disconnect contact studs extends.

2. The low profile switchgear unit of claim 1 wherein said pair of disconnect contacts are arranged generally vertically above one another; the lowermost of said pair of disconnect contacts being generally at the same height as said pair of interrupting contacts.

3. The low profile switchgear of claim 2 in which the electrical clearance distance between said contact ends of said pair of disconnect contacts is greater than the vertical distance between the projected axes of said pair of disconnect contact studs.

4. The low profile switchgear unit of claim 2 wherein said lowermost of said pair of disconnect contacts extends beyond the upper disconnect contact of said pair of disconnect contacts.

5. The low profile switchgear unit of claim 4 wherein said first and second rear vertical surface portions are laterally displaced and parallel, whereby said switchgear unit has a generally L shape and wherein said cubicle has a portion overlying said lowermost disconnect stud and said first vertical rear surface portion of said switchgear unit.

6. The low profile switchgear unit of claim 5 wherein said overlying cubicle portion contains a fixed disconnect contact therein for cooperating with the uppermost of said disconnect contact ends.

7. The low profile switchgear unit of claim 6 wherein the bottom portion of said cubicle contains a second fixed disconnect contact for cooperating with the lowermost of said disconnect contact ends.

8. The low profile switchgear of claim 7 in which the electrical clearance distance between said contact ends of said pair of disconnect contacts is greater than the vertical distance between the projected axes of said pair of disconnect contact studs. 

1. In a low profile, truck-mounted switchgear unit containing at least one pair of interrupting contacts, an operating mechanism for operating said pair of interrupting contacts between an engaged and disengaged position, a racking mechanism for moving said truck-mounted switchgear unit with a switchgear cubicle, and at least one pair of disconnect contacts connected in series with said pair of interrupting contacts; said pair of disconnect contacts each comprising an elongated disconnect contact stud extending horizontally away from respective first and second vertical rear surface portions of said truck-mounted switchgear unit and terminating in respective contact ends; said disconnect contact studs being parallel to one another throughout their entire lengths; said pair of disconnect contact studs being stepped relative to one another, whereby said pair of studs are laterally separated from one another such that the said contact end of one of said disconnect contact studs does not reach the lateral position of the said vertical rear surface portion from which the other of said disconnect contact studs extends.
 2. The low profile switchgear unit of claim 1 wherein said pair of disconnect contacts are arranged generally vertically above one another; the lowermost of said pair of disconnect contacts being generally at the same height as said pair of interrupting contacts.
 3. The low profile switchgear of claim 2 in which the electrical clearance distance between said contact ends of saId pair of disconnect contacts is greater than the vertical distance between the projected axes of said pair of disconnect contact studs.
 4. The low profile switchgear unit of claim 2 wherein said lowermost of said pair of disconnect contacts extends beyond the upper disconnect contact of said pair of disconnect contacts.
 5. The low profile switchgear unit of claim 4 wherein said first and second rear vertical surface portions are laterally displaced and parallel, whereby said switchgear unit has a generally L shape and wherein said cubicle has a portion overlying said lowermost disconnect stud and said first vertical rear surface portion of said switchgear unit.
 6. The low profile switchgear unit of claim 5 wherein said overlying cubicle portion contains a fixed disconnect contact therein for cooperating with the uppermost of said disconnect contact ends.
 7. The low profile switchgear unit of claim 6 wherein the bottom portion of said cubicle contains a second fixed disconnect contact for cooperating with the lowermost of said disconnect contact ends.
 8. The low profile switchgear of claim 7 in which the electrical clearance distance between said contact ends of said pair of disconnect contacts is greater than the vertical distance between the projected axes of said pair of disconnect contact studs. 